Testing Higgs $CP$ properties at the CEPC with an additional ISR parameter

Alexey Drutskoy; Egor Vasenin

high energy physics

Testing Higgs $C P$ properties at the CEPC with an additional ISR parameter

arXiv:2511.06353

summary

The paper studies how well the future CEPC electron‑positron collider can detect a CP‑odd component in the Higgs boson by analyzing the process e⁺e⁻→HZ, using a new method that incorporates the shift in reconstructed event energy caused by initial‑state radiation together with angular observables.

Abstract

We evaluate the experimental sensitivity to the $C P$ -odd admixture in the standard Higgs boson for the process $e^{+} e^{-} \to H Z$ . The analysis is performed assuming the future lepton collider CEPC reference detector operating at $s = 240 GeV$ with statistics of $5.6 ab^{- 1}$ . Using the WHIZARD generator with the Higgs Characterisation model and the DELPHES detector simulation framework we obtain data samples for different $C P$ -odd Higgs admixture parameters $c ~_{Z Z}$ . The initial state radiation (ISR) effects are taken into account in WHIZARD. We develop a novel data-analysis method that exploits the ISR-induced shift in the reconstructed event energy $E_{RECO}$ as an additional source of information on the Higgs $C P$ structure. The method combines the ISR-sensitive event-energy information with three angular observables in a multidimensional likelihood analysis. The expected upper limit on the CP-odd Higgs admixture is improved by 15% compared with the standard analysis based on three angular variables.

8 pages, 7 figures, 2 tables

Topics & keywords

#higgs cp properties #cepc #electron-positron collisions #initial state radiation #multidimensional likelihood analysiscp-odd admixturehiggs characterisation modelwhizarddelphesisr-induced energy shiftangular observables

Testing Higgs CP properties at the CEPC with an additional ISR parameter

Abstract

Topics & keywords

Testing Higgs $C P$ properties at the CEPC with an additional ISR parameter